[llvm] [DWARFLinker][DWARFLinkerParallel][NFC] Refactor DWARFLinker&DWARFLinkerParallel to have a common library. Part 1. (PR #75925)

[via llvm-commits]

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@@ -9,8 +9,9 @@
 #include "DependencyTracker.h"
 #include "llvm/Support/FormatVariadic.h"
 
-namespace llvm {
-namespace dwarflinker_parallel {
+using namespace llvm;
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avl-llvm wrote:

This style is recommended by guidelines for namespaces in source file : https://llvm.org/docs/CodingStandards.html#use-namespace-qualifiers-to-implement-previously-declared-functions.
Here is the example of using it in codebase - https://github.com/llvm/llvm-project/blob/780a5116ba68ec8c53b65008b3407479478b2d5e/llvm/lib/DebugInfo/GSYM/DwarfTransformer.cpp#L26

The patch changes namespace structure so we need to update this place anyway. So it is updated using the recommended form.

https://github.com/llvm/llvm-project/pull/75925